1. Field of the Invention
The present invention relates to a manufacturing method of an absorbent article and a manufacturing apparatus of an absorbent article, in which a filiform elastic member is arranged in a cross direction crossing a predetermined direction, at least partially in a front waistline region, a back waistline region, and a crotch region.
2. Description of the Related Art
Conventionally, the manufacturing process of an absorbent article such as a disposable diaper widely uses a method of arranging a filiform elastic member (rubber) having stretching properties at least partially in a front waistline region, back waistline region, and crotch region of the absorbent article, in order to improve the fittingness to a wearing target (for example, a human body).
Specifically, in the manufacturing process, the elastic member is arranged in a waveform on a web in which components forming one part of the absorbent article, such as a back sheet or an absorbent sheet are sequentially arranged. That is, the filiform elastic member is arranged in a waveform on a crosswise-flow web in which the longitudinal direction of the absorbent article is arranged along a cross direction (CD) crossing a conveyance direction (Machine Direction (MD)) of the web. Accordingly, the absorbent articles each provided with a gather corresponding to the shape of the crotch region can be continuously manufactured.
As such a method of arranging a filiform elastic member in a waveform on a web being conveyed, known is a method of feeding an elastic member from an tip end portion of an arm member which is directly connected with a rotational shaft of a servomotor, while swinging the arm member in width directions of the web at a predetermined cycle (for example, see Japanese Patent Application Publication No. 2004-159866 (pages 6 to 8, FIGS. 3 and 4)). Since the servomotor is rotatable at high speed, use of such an arm member directly connected with the servomotor leads to improvement of a production rate of the absorbent article.
However, the above-described conventional manufacturing method of an absorbent article has the following problem. Specifically, when an absorbent article with a larger size, for example, a disposable diaper for adults is to be manufactured, an arm member has to be increased in length than that for a disposable diaper for infants. However, the increase in length of the arm member brings about an increase of a weight thereof, thereby posing a problem that it is difficult to rotate the servomotor at desired speed.
On the other hand, the arm member may be manufactured with a longer length but light weight. In this case, however, rotating the arm member at a desired speed may damage the arm member, because the arm member itself cannot endure the acceleration.